Toner External Additive Penetration Control for Transfer Efficiency
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Solution Overview
Problem
In electrophotographic processes, the use of low-strength paper or paper with fillers leads to paper dust adhesion issues on photosensitive members, causing charging defects and reduced transfer efficiency, especially in low transfer current conditions, where conventional toners with large external additives fail to maintain spacer function and adhesion.
Innovation Solution
A toner with an external additive of Feret diameter between 60 nm to 200 nm, made of inorganic fine particles or organic-inorganic composite fine particles, is designed to have a specific penetration depth and protrusion height, ensuring strong adhesion and controlled penetration to enhance transfer efficiency without scatter, using a mixing processor that applies heat for adhesion without impact or shear forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If transfer current is reduced to suppress paper dust adhesion, then paper dust adhesion is reduced, but transfer efficiency drops
Solution Approach 1:
The patent changes the physical parameters of the external additive (particle size, shape, material composition) to optimize both paper dust suppression and transfer efficiency. Specifically, using inorganic fine particles with controlled size distribution and surface properties allows the system to maintain adequate transfer current while reducing paper dust adhesion through improved toner-paper interaction
Solution Approach 2:
The patent employs composite external additives consisting of inorganic fine particles (such as silica, alumina, or titania) combined with organic materials. This composite structure provides both the spacer function needed to prevent paper dust adhesion and the adhesion properties required to maintain transfer efficiency, resolving the contradiction between these two opposing requirements
2Strength
If external additive penetrates deeply into toner particle, then adhesion is strong, but spacer function is insufficient
Solution Approach 1:
The patent applies local quality by creating a non-uniform distribution of external additives within the toner particle structure. The surface region contains sufficient external additive concentration to provide strong adhesion, while the interior maintains appropriate porosity and structure to preserve spacer function. This localized differentiation resolves the contradiction between adhesion strength and spacer effectiveness
3Length of moving object
If external additive of large particle size is used, then spacer function is improved, but deep penetration occurs reducing effectiveness
Solution Approach 1:
The patent segments the external additive population into different particle size ranges and distributes them strategically within the toner particle. Larger particles (providing spacer function) are positioned primarily at the surface, while smaller particles penetrate deeper into the toner matrix. This segmentation approach allows both spacer function and adhesion to be optimized without the drawbacks of using uniformly large particles
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The toner achieves improved transfer efficiency for line images under low transfer current conditions by maintaining a stable spacer function and preventing toner scatter, while ensuring strong adhesion and mechanical strength, thus addressing the limitations of conventional toners.
Implementation Method 1
using a mixing processor that applies heat for adhesion without impact or shear forces
Data Source
AI summary
A toner comprising a toner particle including a binder resin and a colorant and an external additive, wherein the external additive contains an external additive A having a Feret diameter of 60 to 200 nm, the external additive A is inorganic fine particles or organic-inorganic composite fine particles, adhesion index of the external additive A to the toner is 0.00 to 3.00, and penetration depth b and protrusion height c satisfy Relational expressions (1) and (2) below, where b (nm) denotes penetration depth of the external additive A, at a portion of the external additive A penetrating into the toner particle interior from the surface thereof, and c (nm) denotes a protrusion height of the external additive A at that portion, in an observation of an image resulting from image processing of a cross section of the toner using TEM;60≤b+c≤200 (1),0.15≤b/(b+c)≤0.30 (2).